The present technology relates to gas turbine components and a method for machining gas turbine components. More specifically, the present technology relates to systems and methods for machining of gas turbine components during production and repair or reconditioning of these gas turbine components.
Gas turbine components haveing an internal cavity—subsequently referred to as first inner cavity—are already known. An example of such a configuration is a blade, like a guide vane or turbine blade of a gas turbine or of an aircraft engine, which is provided with a first inner cavity for cooling purposes. Such a first inner cavity, which can also be designed as a channel, an arrangement of several cooperating channels, a chamber and/or a chamber system, can have one or more undercuts and can then be connected to holes or slits, so that the entire arrangement of inner cavity and holes or slits permits air flow through the blade. Such blades are also referred to as internally cooled or internally air-cooled blades.
In the production and repair of such blades, a number of machining steps is typically carried out. For example, it can be prescribed that one of the machining steps conducted in the context of production is “casting” in the blade, in which the first inner cavity is formed in the context of this casting process. The first inner cavity, however, can also be formed in a different way. Holes or cooling holes or slits or cooling slits are generally introduced after formation of the mentioned first cavity. This can be so that by means of a mechanical machining method, like drilling, cooling holes are introduced that extend from the outer surface of the blade to the first cavity. Another possibility is to introduce such holes or slits by means of a laser. While it can be relatively easily ensured that the limitation section of the first cavity opposite the hole being formed will not be adversely affected or damaged during the mechanical drilling of a cooling opening, it is much more difficult to ensure during laser drilling. During mechanical drilling, an adverse effect on the mentioned opposite wall section can be simply avoided by controlling the drilling depth, however, during laser drilling, there is a not insignificant hazard that the laser radiation will produce undesired changes on the opposite wall section of the cavity limitation.
The effect area, or the area upon which the laser drilling is intended to have a drilling effect, is not only in the area in which the laser drilling influences, as laser drilling also affects the wall section of the first cavity opposite the laser drilling. It is desirable, however, to avoid or reduce the adverse effects or changes that occur in the opposite wall section as a result of laser drilling.
This problem of having effects occur in areas of the component, or the gas turbine component in which effects are undesired during the production or repair of gas turbine components by machining steps or by a machining tool, however, does not only exist during the mentioned laser drilling.
This problem can also occur, for example, during coating of gas turbine components—be it in the context of the manufacturing process or in the process of repair. If, for example, an internally air-cooled blade is at least partially de-coated in the context of repair work and then re-coated, there is a hazard that during this coating, the cooling air holes will be clogged or their cross-sectional areas at least reduced.
Here again, during a machining step, namely coating, an effect occurs on an area of the component or blade in which the corresponding effect is undesired.
The underlying task of the presently described technology is to devise a method for machining especially internally cooled or internally air-cooled gas turbine components, where the machining occurs during production or repair of these gas turbine components, in which the hazard of undesired or damaging effects is reduced or even avoided during the machining steps on the gas turbine component.